Not sure, but I suspect the US builds each AC-130 from the ground up from the production stage (i.e., it doesn't mod existing C-130s). It would make sense because those aircraft have a specific sensor and weapons-compatibility stack. Not only that, but the real "punch" is the 105 mm gun, and I don't know if pairing that (with its feedback, momentum, etc) to the regular Herc is feasible. The AC-130 is basically one-of-a-kind.
The closest outside vendors got is building lighter applications by modding the C-295, C-27J, and An-132. You won't get the 105 mm gun with any of those, but you do get a decent load-out via a 35 mm cannon plus limited ATGM and PGB-carrying capability. I suspect the PAF never went with any of these options because they were still too niche to justify procurement (as doing so would take funds away from a general-purpose logistics asset).
That said, given the chronic and perpetual instability in our Western front, I think we need to form permanent service arms for each of COIN, CT, Anti-Narc, Anti-Smuggling, etc. I can see a powerful federal police force manage CT, Anti-Narc, Anti-Smuggling/Trafficking (akin to Canada's RCMP). However, COIN will need a standing military force comprising of regular infantry, MRAPs, LAVs, UAVs, fixed-wing strike aircraft, and niche assets (like AC-27J, ISTAR, etc).
IMHO, ideally, we'd rework our existing paramilitaries into a unified National Guard (for COIN) and a National Police Force (for CT/Narco/Smugg/f). You'd bracket these two forces with the ISI to form a 'National Security' cluster to mirror 'National Defense' (i.e., Army, Navy, Air Force, SPD).
@SQ8 @Signalian
In turn, you'd have a Chief of Nat-Sec and a Chief of Nat-Def.
Anything regarding India runs through the Chief of Nat-Def, while internal instability goes to the Chief of Nat-Sec. I think this could be a way to delineate the decision-making, skills, and human resources aspect between the two. You'd avoid the risk of military leaders muddling the two and ensure that we have a full-time focus on both.
Moreover, the culture for handling internal threats isn't the same as fighting a standing military force. Nat-Sec could focus on things like intelligence, busting financial streams, deeply studying local culture environments, pre-empting threats, creating civil buy-in, etc.
